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EGT - single/twin scroll - max values

EFI Tuning Fundamentals

Discussion and questions related to the course EFI Tuning Fundamentals


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Hi there,

last weekend I did some 1/4 mile races and collected alot of data which I inspected.

I have some general questions regarding EGT.

I have installed 4 EGT sensors directly post cylinder head on each cylinder, and 2 pre turbo as I have a twin scroll turbo.

now my questions: :-)

1.) I talked to a friend regarding this topic and he told me that a twin scroll shows higher EGT pre turbo than a single scroll. Is that right and how much does it differ?

2.) Under full boost in 4th gear, I finish with an EGT pre turbo at about 890 C°. How would you rate this value

3.) which comes to my next question: How high should the EGT be on a drag race pre turbo in maximum?

4.) also my air temperature raises in the end to 52C°. I will make an update to lower this. Does a lower air temp has effect on lower EGT? Or is it non relevant?

Thanx alot :-)

Cheers

Cyril

One of the first factors to consider is that EGT is very dependent on fuel. For a pump gas fuel, 890 C is up there but not dangerous. Most turbos will handle 950 C although some now will handle over 1000. If you were seeing this sort of EGT on methanol fuel however you'd be picking up melted pieces of piston from the track. E85 is somewhere in between in terms of the EGT that's tolerable.

With regard to twin scroll vs single, I don't have back to back data to give you any guidance here unfortunately however if the exhaust back pressure is comparable between the two styles of housing I'd see non reason for the twin scroll to read higher.

Anything that effects combustion heat will impact the EGT so IAT can play a part however it's not going to be significant. I'd say however that 52 C IAT is very high and costing you power at a minimum.

Hi Andre

thank you very much vor your comments.

I am also of the opinion that 890C pre turbo are not too dangerous

I use 102 octane pump fuel which is pretty common here in germany

regarding my IAT I will try a spraybar on my intercooler and see the result

however, a water methanol injection is also an option

thanx again!!!